A stud girdle would only be needed for instances that you would be using a camshaft that required very heavy spring pressures(big solid lift or roller) and high RPM. If you are planning to machine your head for screw-in studs, you can upgrade to 7/16" studs and be safe with that and not need a stud girdle. The purpose of a turbo is to make a lot of HP lower in the RPM range so you do have to rev the engine to the moon to make the same HP.
